Semax vs PT-141: ACTH Analog vs Melanocortin Peptide Comparison | Peptpedia
This comprehensive analysis compares Semax and PT-141 based on peer-reviewed clinical research, examining their mechanisms of action, efficacy data, and safety profiles. For complete individual peptide profiles, visit the dedicated research pages linked above.
Semax and PT-141 share ACTH/alpha-MSH origin but represent pharmacologically distinct agents. Semax (Met-Glu-His-Phe-Pro-Gly-Pro) is an ACTH(4-7) analog registered in Russia as a cognitive and neuroprotective agent; PT-141 (Bremelanotide) is an FDA-approved cyclic melanocortin peptide developed for sexual dysfunction. Both activate melanocortin receptor pathways, but with completely different clinical targets: Semax for CNS BDNF upregulation and neuroprotection; PT-141 for MC3R/MC4R-mediated sexual arousal.
Chemical Identity
Side-by-Side Comparison
| Property | Semax | PT-141 |
|---|---|---|
| Origin | ACTH(4-7) sequence + Pro-Gly-Pro stabilization | Cyclic alpha-MSH analog (from Melanotan II) |
| Primary Target | BDNF/NGF upregulation, ACTH-like receptors | MC3R/MC4R (central melanocortin receptors) |
| Clinical Use | Cognition, neuroprotection, stroke (Russia) | HSDD in premenopausal women (FDA-approved) |
| FDA Status | Not approved (registered in Russia) | Approved (Vyleesi, 2019) |
| Melanocortin Selectivity | Low MC direct agonism; indirect BDNF pathway | High MC3R/MC4R selectivity; low MC1R |
| Tanning Effect | None significant | Minimal (poor MC1R affinity) |
| Administration | Intranasal drops (primary) | Subcutaneous injection (auto-injector) |
Shared Melanocortin Heritage: ACTH vs Alpha-MSH
Semax is derived from the ACTH(4-7) sequence (His-Phe-Arg-Trp)—the minimal core of ACTH required for receptor binding—with the stabilizing Pro-Gly-Pro extension added to increase CNS penetration and metabolic stability. Its primary mechanism is stimulation of BDNF and NGF synthesis in hippocampal and prefrontal cortical neurons through ACTH receptor interactions, with downstream effects on synaptic plasticity, neurogenesis, and neuroprotection. It has minimal classical melanocortin receptor agonism.
PT-141 is a cyclic analog of alpha-MSH (also derived from POMC), engineered to maximize MC3R and MC4R binding while minimizing MC1R activation (tanning) and hypertensive effects that limited Melanotan II's development. Its primary action is on hypothalamic and limbic MC4R to activate sexual arousal circuits through a CNS mechanism completely distinct from peripheral vasodilatory drugs like PDE5 inhibitors.
Frequently Asked Questions
Research Citations
Bremelanotide for female sexual dysfunctions in premenopausal women: a randomized, placebo-controlled dose-finding trial
Clayton AH, Althof SE, Kingsberg S, et al. (2016). Women's Health